Gossip Protocol¶

How nodes maintain consistent network state.

Overview¶

StreamSync uses a gossip protocol for:

Node discovery
Health monitoring
State synchronization
Failure detection

Protocol Modes¶

Push-Pull (Default)¶

Combines push and pull for best consistency:

sequenceDiagram
    participant A as Node A
    participant B as Node B

    A->>B: Push: My state updates
    B->>A: Pull: Request your full state
    A-->>B: State digest
    B->>B: Merge states

Configuration¶

[gossip]
protocol = "push-pull"
fanout = 3
pull_interval_seconds = 5
heartbeat_interval_seconds = 1
failure_threshold_missed_heartbeats = 5

Message Types¶

Message	Purpose
`Heartbeat`	Liveness check
`Push`	Send state updates
`Pull`	Request state
`Sync`	Full state sync
`Suspect`	Report suspected failure

Failure Detection¶

stateDiagram-v2
    [*] --> Alive
    Alive --> Suspect: 3 missed heartbeats
    Suspect --> Alive: Heartbeat received
    Suspect --> Dead: 5 missed heartbeats
    Dead --> Alive: Recovery detected

Suspected nodes are: - Excluded from query routing - Gossiped to other nodes - Monitored for recovery

Network Ports¶

Port	Protocol	Purpose
7878	UDP/TCP	Gossip messages
7879	TCP	State sync

Tuning¶

Parameter	Low Latency	High Consistency
`fanout`	2	5
`heartbeat_interval`	500ms	2s
`pull_interval`	10s	2s